Last fall, authorities arrested hundreds of call center employees in the Mumbai suburb of Thane for their alleged involvement in these scam calls, but the 24-year-old head of the operation fled the country. Reutersreports that he was arrested over the weekend at an airport in Mumbai after getting off a flight from Dubai, where he’d been living since December.

Thane Police Commissioner Param Bir Singh said he had interrogated the suspect — who he says confessed his involvement in the scheme — and is “impressed with his knowledge of the U.S. and Indian system.”

In October, police in the city of Thane were tipped off by a disgruntled call center employee that the call centers in question were calling American phone numbers, claiming to be from the IRS and telling their victims that they had defaulted on their tax debt and must now pay — anywhere from a few hundred dollars to several thousand dollars, which would be remitted via prepaid cash card.

Police say the scammy call centers were raking in anywhere from $150,000 to $225,000 each day, and that the operators of this scam brought in around $75 million in a little more than a year.

There could be victims outside the U.S. as well, Singh said at the time, and Americans may be involved in the scheme.

Around 400 people have since been charged in the case, and about a dozen of them are in custody, Singh says.